The long-range goal of this project is to develop and validate the CD1-based vaccine technology platform to immunize humans against microbial pathogens. This approach is based on the knowledge that several of the CD1 proteins have specific targeting sequences that direct their traffic into endosomal compartments, structures also critical for antigen presentation by MHC class II molecules to CD4+ T cells. We will determine whether this novel vaccine strategy can induce protective immunity against Mycobacterium tuberculosis, a worldwide killer, and now because of multi-drug resistant tuberculosis, a potential agent of a bioterrorist attack. We propose to determine the trafficking pattern of CD1 chimers in antigen presenting cells including monocytes and dendritic cells. The ability of CD1 targeting to be used in immunization in humans will be assessed by studying the immune response to an M. tuberculosis antigen ESAT-6. In addition, the ability of ESAT-6/CD1 fusion constructs to immunize human T cell responses in vitro will be investigated. To determine whether ESAT-6/CD1 chimers can induce protective immunity, ESAT-6/CD1 fusion constructs will be used to immunize mice, which will be subsequently challenged with virulent M. tuberculosis. The studies proposed will help develop and test the efficacy of CD1-based DNA vaccines for the prevention of infectious disease, including those from natural pathogens and bioterrorist attacks. Specifically, it should be possible to develop a new approach to the prevention of tuberculosis, including multidrug resistant tuberculosis, in humans. Finally, the CD1-based vaccine technology should prove useful in the vaccination against microbial pathogens in which MHC class II-restricted presentation of antigen to CD4+ T cells is required for host defense.